Highway passenger travel—by automobiles, motorcycles, and light trucks—represented 85 percent of all
passenger-miles and 91 percent of passenger travel energy use in 2000. Highway travel was 2 percent more energy efficient in 2000
compared with 1990 [1]. This gain was due to a 6 percent increase in the energy efficiency of passenger cars and motorcycles, offset
by a 5 percent loss in efficiency of light trucks1[2]. Furthermore, light truck passenger-miles grew 47 percent between 1990 and 2000,
compared with 12 percent for passenger cars and 22 percent for all highway passenger vehicles.

Freight energy efficiency (ton-miles per BTU) declined 7 percent from 1990 to 2000 (figure 118). The decline in
freight energy efficiency occurred as a result of 2 percent average annual growth rate in ton-miles paired with a relatively rapid
average annual growth rate of 3 percent in freight energy consumption. Contributing to this trend was the decline in the energy efficiency of the freight
truck and waterborne modes [2].

1. U.S. Department of Transportation, Bureau of Transportation Statistics, National Transportation Statistics 2002 (Washington,
DC: 2002), calculation based on tables 1-34, 1-44, 4-6, and 4-8, also available at http://www.bts.gov/, as of May 2003.

2. U.S. Department of Transportation, Bureau of Transportation Statistics, Transportation Energy Efficiency Trends in the 1990s,
Issue Brief, available at http://www.bts.gov/, as of May 2003.